Beirut, Aug. 31: In Hezbollahs inner circle, they called him The One Who Never Sleeps.

Imad Mughniyah was one of the most hunted men in the world. Western security forces spent 25 years pursuing the Hezbollah warlord, the alleged mastermind of infamous attacks of the late 20th century and a pioneer of brutal tactics later emulated by al Qaida. In fact, he may have proved a more disciplined, effective master of asymmetric warfare than even Osama bin Laden.

Mughniyah survived through anonymity: changing hide outs, moving without bodyguards or drivers, a pistol always in his belt. On the evening of February 12, he left a safe house in the Kfar Soussa neighbourhood of Damascus, a warren of nearly identical towers that house the employees and headquarters of Syrias vast intelligence apparatus.

He had just held a sit-down with a Syrian spy chief and was preparing for a secret meeting that night with President Bashar Assad, Western anti-terrorism officials say.

Seconds after Mughniyah got behind the wheel of his car, an explosion incinerated him. The assassination in the heart of an authoritarian state ended his bloody odyssey through the modern history of terrorism.

His death at 45 remains as mysterious as his life.

Mughniyahs role at the hub of a murky alliance of Hezbollah, Syria and Iran made him powerful but vulnerable, anti-terrorism officials say. The likeliest scenario is that Israel eliminated him. But the aftermath has reinforced signs of potential Syrian involvement and exposed tensions among Syria, Iran and Hezbollah, Western officials say.

Iran and Hezbollah have sworn revenge, putting Israel on worldwide alert for the kind of attacks that were once Mughniyahs trademark.

The aftermath of Mughniyahs death offered a rare look at apparent tensions among Syria, Iran and Hezbollah.

Syrias deputy foreign minister popped up in Tehran. Irans foreign minister announced a joint investigation. One of Mughniyahs two widows denounced the Syrians as traitors, suggesting that they had a hand in the killing, then retracted the remark.

Finally, the Syrians said they would investigate. But they let an April deadline pass without comment on the inquiry. And Shawkat, a once-powerful ally of Iran, was excluded from the investigation, Western officials say.

Syrias behaviour contrasted dramatically with the threats against Israel by Iran and Hezbollah. The government in Damascus has entered indirect peace talks with Israel and kept a tight lid on the investigation.

Some believe that Syrian leaders played a role in Mughniyahs death, perhaps as part of a deal with the West. The scenario of an assassination by the Israelis does not rule out Syrian involvement, a western security official said.

I wouldnt be surprised if the death of Mughniyah was part of an internal struggle, said the official.

Why would Syria want to get rid of Mughniyah? One theory is that the US and Israel exerted pressure on Damascus. They had leverage: an international courts pending investigation of Syrian leaders in the killing of Lebanese leader Rafik Hariri in 2005. Assads innermost circle may have decided to accept a hit on Mughniyah in exchange for protection from indictments and for improved relations with the West, officials and experts say.

A simpler theory: Mughniyah somehow crossed his Syrian patrons and paid for it.

In south Beirut, meanwhile, a shrine draws mourners at all hours. The enclosure resembles a large outdoor restaurant assembled with cheap materials from a garden or hardware shop. Plastic flowers decorate a tomb at the centre of a plot of artificial grass that covers the graves of about 100 fighters.

On a recent afternoon, a bare-headed woman in a hot-pink shirt entered and knelt at the tomb. She touched it gently, then got up and left the place where Mughniyah finally sleeps.